Last week I needed help with Powertip PG128128A LCD but nobody bothered to answer for about three days.Anyway, the problem was the contrast voltage which had to be around -12V.So...I made a lightly modified charge pump.It has an output of about -16V from a +5V input, a maximum current of 10mA (beyond this point voltage drops significantly) and fits on a piece of 6*4cm of test board.Anyone having problems with the contrast circuit feel free to use this schematic.R3 is a 10k pot for manual contrast adjustment.

Last week I needed help with Powertip PG128128A LCD but nobody bothered to answer for about three days.

Did you ask about it in this forum ? I just tried to look around but didn't see anything like that.
Anyway it's not that strange in a forum like this that you won't get answer immediately. I for example haven't had time to be here in the last four days. Sometimes posts can be also missed and then noticed weeks later...
But looks like you solved your problem yourself